Mezzotint, a printing process of the intaglio or engraving family, is one of the most physically demanding printmaking media: a plate (usually of copper or steel) is “rocked” with a curved, saw-toothed blade until its surface is entirely pitted and burred to hold ink. Typically, a plate is rocked in eight to sixteen directions to achieve an even ground. When fully rocked, a field of metal burrs is created, and when inked and printed, the plate produces a deep uniform black print. A scraper or burnisher is then used to cut away or flatten the raised parts controlling the amount of ink retained around the burrs.
Mezzotint is a reductive process in which the image is created by working from dark to light. The rocked plate initially produces a full black tone when printed. Successive scraping or burnishing progressively produces dark grays, then light grays, and ultimately, white when the surface is completely smooth and can hold no ink. Colors can be added by scraping, burnishing and scoring a separate plate for each color used.
A Dutch amateur printmaker, Ludwig von Siegen, is believed to have originated mezzotint around 1640. The process gained favor in England where it became widely used in the early 1700s for the reproduction of paintings, especially landscapes and portraits. Eventually, the mezzotint process was supplanted with the advent of photography and has seen much more limited use over the last century.
Classically, plates were roughened by rubbing the surface with fine metal filings. The modern process typically involves the use of a steel rocker having a serrated or toothed blade in a shallow curved shape and a wooden handle projecting up from the steel blade. Rockers are commercially available in a range of sizes. Typically, commercially available mezzotint rockers have two and a half inch or five inch blades anywhere from forty-five to a hundred and twenty teeth per inch along the serrated edge of the blade.
The teeth of the serrated blade, when progressively rocked steadily from side to side along the edge of the blade on an engravable surface, cut rows of holes that push up small ridges of metal called burrs. Repeating this rocking across the entire length and width of the plate and then at right angles, or at several other angles to the original direction, produces a plate that is uniformly roughened, or engraved across its surface. When fully rocked across the entire surface of a plate, a field of burrs is created, which when inked and printed results in a solid velvety, black print.
Preparation of a single high quality 2 ft×3 ft plate can take hundreds of hours of exacting and laborious hand rocking. This enormous time commitment by the plate preparer is due to the necessity of rocking in each of the multiple directions in order to achieve an optimum smooth, deep and even print tone. Motorized devices have been produced to alleviate this long and arduous prerequisite process. However, plates produced by the machines available to date lack the rich velvety tones of hand worked plates. Specifically, the rich tones of hand-worked plates is likely due to the play of the rocker from side to side as well as along the direction of the blade. Hand rocking produces slightly variable indentations and the side to side play tends to throw up larger burrs than simple back and forth rocking. By contrast, the available motorized rockers generally produce uniform indentations and smaller burrs due to the more rigid repetitive motion with pressure bearing directly down on the metal. See, for example, the descriptions in “The Mezzotint, History and Technique” by Carol Wax, 1990, Harry N. Abrams, Inc., New York. pp. 179-190.
Other motorized devices have been limited in the size of the plates that can be accommodated, and in the available angles at which they can be rocked.
The engraved plates are then worked by artists to produce mezzotint prints. Where lighter areas are desired, the artist progressively cuts away or smoothes the raised portions and, or shaves the surface to remove indentations. These smoothed and/or shaved surfaces provides less and less accommodation for the ink that is ultimately transferred to the print and thus produces lighter and lighter tones in these areas of the work.
Mezzotints are prized for their range and richness, and also for their smoothness of tone, but preparation of the uniformly roughened plates is arduous when rocked by hand and generally gives less satisfactory results when produced mechanically without human intervention as the richness of tone is lost as a result.